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RODONR.O.S.E. Informatik GmbHAll rights reserved

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RODONRODON RTolerance Based Simulation & Automated FMEA

generation in AircraftElevators

4th Annual Systems Engineering ConferenceDallas, October 22 - 25, 2001


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Our basic approach:

- Seamless math-based data flow from Engineering data to FMEA and Service

Information

This leads to:

- Reduced costs

- Lower development costs for FMEA & Service Information (FDI) generation

- Improved Quality

- More complete and accurate FMEAs & Troubleshooting Procedures

- Reduced Lead times

- Design validation early on in the development process

- Early Availability of Service Information (FDI)

Engineeringdata base


- FMEA- FTA- SCA- FDI- DT

How to improve supportability, affordable readiness &

RTOC ?


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By using a software tool which allows

- To create a simulation model of a system based on its

- Functional behavior

- To have analysis capabilities available for

- Validation of functional design & Risk analysis

- Diagnostics (FDI)

- Non-functional attributes

- like cost, mass for early on requirements analyses

- Failure probability on component level for FTA

=> Both requirements are fulfilled by the model-based software tool RODON

How can a math- based seamless data flow beachieved?


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Simulation,ConsistencyChecks

RequirementsAnalysis

Risk Analysis- FMEA- SCA- FTA- other

Engineering data base:Net lists, Communication TablesNet lists, Communication Tables, Component behavior, ECU Behavior

RODON - Application Areas

Requirements,Specifications

Design & Dvlpmnt.

Integration &Prototyping

Manu- facturing

Maintenance, Operational

Service

RODON is a Software-Tool for System Integration based on theanalysis of the functional behavior of the components

Diagnostics- Model based (MBD) - On Board - Off Board

- Model supported (MSD) - Decision Trees - Diagnostic Rules - State Based Reasoning

Monitoring

RODONVirtual

Product ModelVPM


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RODONModeling I - Components

Relays

Electrical

Mechanics

ECU'sHydraulics

Pneumatics

CableSwitches

On/OffSwitch

Model Description - Transfer Functions

Model Visualization


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Highlights & Features:- Description of Nominal Behavior- Hierarchical Model Structure based uponBOM- Multidirectional Determination of all Values of the System- Qualitative and quantitative Values- Representation of Tolerances as Intervals- Steady State and Dynamic Analyses- Top-Down and Bottom-Up Approach- Definition of Failure Modes on Component Level- Straight Forward Variant Handling

RODONModeling II - Connectivity, Assemblies and Systems

Monitoring Diagnosis

Execution of Analyses

Rqmts Analysis Simulation Risk Analysis

Connectivity on Component and Assembly Level

Modeling I


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•Net lists•Communication Tables•ECU Behavior•Component Behavior


•Net lists•Communication Tables•ECU Behavior•Component Behavior

CAD Schematics RODON State Database

State Data BaseGeneration

RODONSimulationSystem

Model Based Diagnosis

FMEA

RODON Decision Tree

RODONCompressor &Formatting-System

Generation of• Risk Analyses• Diagnostic Knowledge

Results ofAnalyses

•FMEA•FTA•SCA•Decision Trees•Diagnostic Rules

Diagnostic Rules

The RODON Process• Generates Models Automatically from Design Data

• Generates all Analyses by calculation from one Model

RODONModelingSystem

Modelingprocess

RODON System Model


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Example: Project with Aircraft Manufacturer Aircraft Elevator - Fly by wire system

System consists of:- Hydraulic control loop- Controller Logic- Electrical Wiring


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Tasks:- Simulate maximum deviation of actual value from set point depending on tolerances & offsets of inputs- Investigate impact of tolerances & offsets on behavior of monitors- Investigate impact of failure modes on behavior of monitors

Methodology:- Create RODON Virtual Product Model- Simulation with Tolerances for time-dependent systems- Failure-Mode-Simulations for time-dependent systems

Additional benefits concurrently to the simulations:- Automated FMEA generation for dynamic systems- Generation of Troubleshooting Procedures

Example: Aircraft Elevator - Fly by wire system


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Example: Aircraft Elevator - Fly by wire systemCreate RODON Virtual Product Model


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- Sensor-tolerances- Offsets

Elevator position versus time afterstimulation with a step function.

Black: no offsets & tolerancesYellow / cyan: upper boundary of tolerances & offsetsRed / green: lower boundary of offsets and tolerances

Servo-valve position versus time,controlling the elevator position.

Example: Aircraft Elevator - Fly by wire systemTolerance-Simulations with RODON


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Elevator position versus time. „Run-away“situation.Failure-mode is Enabling Valve EV1„STUCK_ACTIVE“.Effect: Main Servo Valve is closed; no controlpossible. Elevator runs away due to air loads. Servo Valve position versus time for all offsets and

tolerances. Position of Servo Valve has no influence onelevator due to closed Main Servo Valve.

Example: Aircraft Elevator - Fly by wire systemFailure Mode Simulations


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Sensor-Monitoring of sensor LVDT of Servo ValveSV. Monitoring behavior as expected.

Position-Monitoring of Servo Valve SV.Monitor activated due to offsets and tolerances.Unexpected Monitoring behavior!

Black curve: Simulation with no offsets and tolerances.Colored curves: Simulations with offsets and tolerances.

Example: Aircraft Elevator - Fly by wire systemExcitation of Monitors


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- Maximum deviation of actual value from set point due to the offsets and tolerances were larger than specified

- Offsets & Tolerances have significant impact on Monitoring for both

- the nominal behavior mode- failure modes

Example: Aircraft Elevator - Fly by wire systemResults of the analysis


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Example: Aircraft Elevator - Fly by wire systemAdditional benefits - FMEA

Potential Effects:

- Observable and measurable

variables of the hydraulic system

Indications:- Monitors- Diagnostic Trouble Codes

System FMEA fordynamic- and tolerance-based systems; generatedautomatically out of thesame RODON VirtualProduct Model.

FMEA was used to checkthe controller‘s selfdiagnostics andmonitors for about 300failure modes.


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Selected Symptoms

• Elevator too high

• Elevator too low

• Elevator stuck

Simplified Fault Trees:Symptom -> possible causesrelationship

Example: Aircraft Elevator - Fly by wire systemAdditional benefits - Simplified Fault Trees


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Automated generation of Troubleshooting Procedures (Decision Trees)out of the same RODON Virtual Product Model.

Example: Aircraft Elevator - Fly by wire systemAdditional benefits - Troubleshooting Procedures


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Additional benefit -Compliance checks for integration and test phases

Manufacturing

StepwiseSpecificationprocess

StepwiseIntegrationprocess

Validation &Compliance checks

“V” - Model

RODON

RODON

RODON

Compliance checks between specifications and the real,physical system according to the “V”-Model can beperformed by using RODON’s Model-Based Diagnosis(MBD) - Function.


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RODON supports the following tasks using the same RODON Virtual

Product Model:

- Analysis of the design

- Automated Risk Analysis: FMEA, simplified FTA, Sneak Circuit

Analysis (SCA)

- Automated generation of troubleshooting procedures and diagnostic

rules

- FDI analysis of the design

- Coverage analysis in the design stage

- Subsystems’ integratability tests by Virtual Prototyping

- Identification of fault conditions for ECU

- “Executable" FMEA with Math Based Model

Summary IRODON-Support to Product Design, Integration & Maintenance


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- Reduces Effort

- To generate FMEA, FTA and diagnostic Information

- Creates “Technical Memory” over successive programs

- Improves Quality:

- More complete and accurate results

by using math based process

- Reduces lead times by early analysis of design

- Getting Errors out Early

- Early Availability: Diagnostic Information available at Integration & Test phase

Summary IIBenefits


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RODON

CAD/3-D

RODONOverall Applications

EngineeringRisk analysesFTA, FMEA…

Integration &System tests

MaintenanceTroubleshootingProceduresforFault Isolation-Component Behavior

-ECU-Communication

CAN-bus Motor

ECUGetriebe

ECU

Manufacturing


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R.O.S.E. Informatik GmbH Major Customers

Aerospace Industry

• ASTRIUM Space Infrastructure• EADS Airbus• NASA Ames Research Center

Automotive Industry

• Volkswagen

• DaimlerChrysler• General Motors (GM)

Military

• Krauss-Maffei Wegmann


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4th Annual Systems Engineering Conference NDIADallas, October 22 - 25, 2001

R.O.S.E. Informatik GmbH

Exhibition Booth #

Contact Address:Dr. Dirk BurowRIG TEK, Inc.Phone: (248) - 209 - 4585Fax: (248) - 209 - 4505e-mail: [email protected]

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RODON - elsmar.com and Reliability Analysis/burow(2... · FMEA RODON Decision Tree RODON Compressor & Formatting-System Generation of • Risk Analyses • Diagnostic Knowledge Results